A digitally-assisted sensor interface for biomedical applications

A compact, low-power, digitally-assisted sensor interface for biomedical applications is presented. It exploits oversampling and digital design to reduce system area and power, while making the system more robust to interferers. Anti-aliasing is achieved using a charge-sampling filter with a sinc frequency response and programmable gain. A mixed-signal feedback loop creates a sharp, programmable notch for interference cancelation. A prototype was implemented in 0.18 µm CMOS and the on-chip blocks consume a total of 255 nW – 2.5 µW from a 1.5 V supply depending on noise and bandwidth requirements.